Iontophoresis is a well-known manner of administering drugs through the skin. See, for instance, U.S. Pat. Nos. 4,744,787, 4,722,726, 4,731,049 and 4,752,285.
The use of rate-controlling membranes in the passive (non-iontophoretic) administration of drugs transdermally is described in U.S. Pat. Nos. 3,598,122, 3,797,444 and 3,966,934.
The use of skin permeation enhancers to increase the permeability of skin to drugs is well known. See, for instance, U.S. Pat. Nos. 4,006,218, 4,568,343, 4,746,515, 3,989,816, 4,316,893, 4,764,379 and EP Publications 272,987, 261,429 and 043738.